At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.Which is the best title for this passage?A.The Possibility of Life on the MarsB.Future Conditions on the MarsC.The Mars and the EarthD.A Study of the Climate of the Mars
At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.
Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.
Which is the best title for this passage?
Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.
Which is the best title for this passage?
A.The Possibility of Life on the Mars
B.Future Conditions on the Mars
C.The Mars and the Earth
D.A Study of the Climate of the Mars
B.Future Conditions on the Mars
C.The Mars and the Earth
D.A Study of the Climate of the Mars
参考解析
解析：文章的标题就是文章的中心。作者从火星上曾经有过生命的证明谈到未来通过提高温度而使火星适合生存的设想，表明文章的中心是：火星具有生命存在可能性。
相关考题：
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At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.There could be life on the Mars in the future ifA.it supported life in the pastB.certain gases are used to cool the planetC.the atmosphere can be heated enough to grow simple plantsD.the planet's volcanoes become as active as they were in the past
At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.The author's attitude towards the possibility of life on the Mars in the future is__.A.doubtfulB.positiveC.negativeD.uninterested
At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.Some scientists think there may have been life on the Mars in the past because__.A.there is no life there nowB.there is a large amount of water at the polesC.the Mars may be able to support life in the futureD.conditions may have been similar to those on the Earth
共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.The word"fraction"in the second paragraph means________.A:a large areaB:a very small amountC:an important systemD:a major source of information
共用题干第一篇Water Resources on the EarthThe second most important constituent（构成成分）of the biosphere（生物圈）is liquid water. This can only exist in a very narrow range of temperatures,since water freezes at 0℃and boils a 100℃．Life as we know it would only be possible on the surface of a planet which had temperature: somewhere within this narrow range.The earth's supply of water probably remains fairly constant in quantity.The total quantity of water is not known very accurately,but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers.Most of it is in the form of the salt water of the oceans一about 97 percent. The rest is fresh.But three-quarters of this is in the form of ice at the poles and or mountains and cannot be used by living systems until melted.Of the remaining fraction,which h somewhat less than one percent of the whole.There is 10—20 times as much stored underground water as there is actually on the surface.There is also a tiny,but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation（循环） of the biosphere has to pass.Water evaporated（蒸发）from the surface of the oceans,from lakes and rivers and from moist（潮湿的）earth is added to it. From it the water comes out again as rain or snow,falling on either the sea or the land. There is,as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land,but there is more rainfall over the land than over the oceans and the balance is restored by the run off from the land in the form of rivers.Liquid water only exists________.A: in the center of the earthB:on the surface of our planetC:in the coastal areas of the earthD:in a very narrow range of temperatures
共用题干A Record-Breaking RoverNASA's Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004,Opportunity has traveled 25 .01 miles,more than any other wheeled vehicle has on another world.“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,”says John Callas,the Mars Exploration Rover Project Manager.He works at NASA's Jet Propulsion Laboratory in Pasadena,California.“But what is really importantly is not how many miles the rover has racked up,but how much exploration and discovery we have accomplished over that distance.”The solar-powered Opportunity and its twin rover,Spirit,landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life,such as the possible presence of water.Spirit stopped communicating with Earth in March 2010,a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.During its mission,Opportunity has captured,and sent back to Earth,some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet's atmosphere,soil,rocks,aid terrain.The rover doesn't seem to be ready to stop just yet. If Opportunity can continue on,it will reach another major investigation site when its odometer hits 26.2 miles. Opportunity has beer working on Mars since January 2004.Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars's ancient environment. Opportunity's continuing travels will also help researchers as the, plan for an eventual human mission to the Red Planet. Which of the following statements is true of Opportunity?A: It will come back to earth soon.B: Another rover will be sent to replace it.C: It is travelling to another major investigation site.D: It will work with other rovers exploring Mars.
共用题干A Record-Breaking RoverNASA's Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004,Opportunity has traveled 25 .01 miles,more than any other wheeled vehicle has on another world.“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,”says John Callas,the Mars Exploration Rover Project Manager.He works at NASA's Jet Propulsion Laboratory in Pasadena,California.“But what is really importantly is not how many miles the rover has racked up,but how much exploration and discovery we have accomplished over that distance.”The solar-powered Opportunity and its twin rover,Spirit,landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life,such as the possible presence of water.Spirit stopped communicating with Earth in March 2010,a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.During its mission,Opportunity has captured,and sent back to Earth,some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet's atmosphere,soil,rocks,aid terrain.The rover doesn't seem to be ready to stop just yet. If Opportunity can continue on,it will reach another major investigation site when its odometer hits 26.2 miles. Opportunity has beer working on Mars since January 2004.Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars's ancient environment. Opportunity's continuing travels will also help researchers as the, plan for an eventual human mission to the Red Planet. Opportunity is a record breaking rover in the sense of________.A: how long is has stayed in spaceB: how far it has traveledC: how much investment it has involvedD: how many facilities it has been equipped with
共用题干A Record-Breaking RoverNASA's Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004,Opportunity has traveled 25 .01 miles,more than any other wheeled vehicle has on another world.“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,”says John Callas,the Mars Exploration Rover Project Manager.He works at NASA's Jet Propulsion Laboratory in Pasadena,California.“But what is really importantly is not how many miles the rover has racked up,but how much exploration and discovery we have accomplished over that distance.”The solar-powered Opportunity and its twin rover,Spirit,landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life,such as the possible presence of water.Spirit stopped communicating with Earth in March 2010,a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.During its mission,Opportunity has captured,and sent back to Earth,some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet's atmosphere,soil,rocks,aid terrain.The rover doesn't seem to be ready to stop just yet. If Opportunity can continue on,it will reach another major investigation site when its odometer hits 26.2 miles. Opportunity has beer working on Mars since January 2004.Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars's ancient environment. Opportunity's continuing travels will also help researchers as the, plan for an eventual human mission to the Red Planet. It can be inferred from the last paragraph that＿________.A: experts know how far Opportunity will make in MarsB:.reseachers are working on sending many more humans to MarsC: Mars's ancient environment might be exposed with the help of OpportunityD: Opportunity is supposed to collect clay minerals from Marathon Valley
共用题干A Record-Breaking RoverNASA's Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004,Opportunity has traveled 25 .01 miles,more than any other wheeled vehicle has on another world.“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,”says John Callas,the Mars Exploration Rover Project Manager.He works at NASA's Jet Propulsion Laboratory in Pasadena,California.“But what is really importantly is not how many miles the rover has racked up,but how much exploration and discovery we have accomplished over that distance.”The solar-powered Opportunity and its twin rover,Spirit,landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life,such as the possible presence of water.Spirit stopped communicating with Earth in March 2010,a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.During its mission,Opportunity has captured,and sent back to Earth,some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet's atmosphere,soil,rocks,aid terrain.The rover doesn't seem to be ready to stop just yet. If Opportunity can continue on,it will reach another major investigation site when its odometer hits 26.2 miles. Opportunity has beer working on Mars since January 2004.Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars's ancient environment. Opportunity's continuing travels will also help researchers as the, plan for an eventual human mission to the Red Planet. What does John Callas say about Opportunity's long distance travel?A: It hasn't met scientists' expectation yetB: It hasn't been appreciated appropriatelyC: It is secondary to what has been discoveredD:.It is what scientists have been aiming at
共用题干A Record-Breaking RoverNASA's Mars rover Opportunity has boldly gone where no rover has gone before—at least in terms of distance. Since arriving on the Red Planet in 2004,Opportunity has traveled 25 .01 miles,more than any other wheeled vehicle has on another world.“This is so remarkable considering Opportunity was intended to drive about 1 kilometer and was never designed for distance,”says John Callas,the Mars Exploration Rover Project Manager.He works at NASA's Jet Propulsion Laboratory in Pasadena,California.“But what is really importantly is not how many miles the rover has racked up,but how much exploration and discovery we have accomplished over that distance.”The solar-powered Opportunity and its twin rover,Spirit,landed on Mars 10 years ago on a mission expected to last 3 months. The objective of the rovers was to help scientists learn more about the planet and to search for signs of life,such as the possible presence of water.Spirit stopped communicating with Earth in March 2010,a few months after it got stuck in a sand pit. But Opportunity has continued to collect and analyze Martian soil and rocks.During its mission,Opportunity has captured,and sent back to Earth,some 187,000 panoramic and microscopic images of Mars with its cameras. It has also provided scientists with data on the planet's atmosphere,soil,rocks,aid terrain.The rover doesn't seem to be ready to stop just yet. If Opportunity can continue on,it will reach another major investigation site when its odometer hits 26.2 miles. Opportunity has beer working on Mars since January 2004.Researchers believe that clay minerals exposed near Marathon Valley could hold clues to Mars's ancient environment. Opportunity's continuing travels will also help researchers as the, plan for an eventual human mission to the Red Planet. One of the objectives of sending Opportunity and Spirit is to＿________.A: collect soil and send back to EarthB: develop multinational space explorationC:.test how well solar-powered rovers work in outer spaceD: look for the possible presence of life
I spent most of my money in the first week and（）had very little for food at the end of the holiday.AsinceBhoweverCmoreoverDconsequently
单选题In the Northern hemisphere northerly winds may cause temperature（）.AfallingBrisingCconstantDsame
单选题The second stage feed-water temperature and shell absolute pressure in a multistage, flash type, distilling plant is （）Ahigher than the first stage feed-water temperature and absolute shell pressureBlower than the first stage feed-water temperature and absolute shell pressureCthe same as the first stage feed-water temperature and absolute shell pressureDnot related to the feed-water temperature and absolute shell pressure
单选题I spent most of my money in the first week and（）had very little for food at the end of the holiday.AsinceBhoweverCmoreoverDconsequently
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单选题Cloud formations are minimal when the（）.Asurface temperature and temperature aloft are equalBsurface temperature and temperature aloft differ greatlyCbarometric pressure is very lowDrelative humidity is very high